The present invention relates to a brush device for bringing a brush into contact with a commutator. The invention also relates to a motor including the brush device.
A motor disclosed in Japanese Laid-Open Patent Publication 2010-124518 includes a brush device provided with a feed brush, which comes into contact with the outer peripheral surface of a commutator. The commutator is fitted over and fixed to a rotary shaft, which is rotated. A brush-tip end comes into contact with the outer peripheral surface of the commutator. The brush device further includes a cylindrical brush holder, which holds the brush inside thereof, and a spring, which urges a brush-rear end toward the commutator. In some cases, such a brush device uses a torsion spring as the spring, which urges the brush-rear end. If the torsion spring is used, the brush device can be made compact as compared with a case where a coil spring is used, for example. Generally, the torsion spring presses one point against a rear end surface of the brush, thereby urging the brush toward the commutator. The interior space of the brush holder is formed slightly larger than the outside shape of the brush, taking thermal expansion of the brush into account. Hence, when the rotary shaft is rotated, i.e., when the commutator is rotated, there is a problem in that the orientation of the brush is not easily stabilized in the brush holder and the contact state between the brush-tip end and the commutator becomes unstable.
To solve such a problem, according to the brush device described in Japanese Laid-Open Patent Publication 2010-124518, to bring the brush into contact with the commutator in a stable state, the brush-rear end is provided with a plate-like pressing member. By urging the pressing member by the torsion spring, the urging force of the torsion spring is transmitted to the brush through the pressing member.
According to the brush device described in Japanese Laid-Open Patent Publication 2010-124518, however, the torsion spring presses with its one point against the pressing member. Hence, the urging direction of the torsion spring against the pressing member is not easily stabilized. Therefore, the direction in which the brush is urged through the pressing member is not easily stabilized either, and the brush may rattle the brush holder, i.e., the brush moves irregularly. According to such a brush device, since the pressing member is additionally provided between the spring and the brush, the number of parts is increased.
It is an objective of the present disclosure to provide a brush device and a motor capable of suppressing rattling of a brush without increasing the number of parts.